P344	Role of inflammation on dendritic cells and vascular smooth muscle cell interactions.
M.C.Vinci, L.Bellik, F.Ledda, A.Parenti
Pharmacology Department, University of Florence, Florence, IT.

Atherosclerosis is an inflammatory disease characterized by specific cellular and molecular responses in the lesions. Dendritic cells (DCs), which play a crucial role in the initiation of an immune response, have been described in atherosclerotic lesions. The CD40-CD40 ligand system, involved in DC-T lymphocyte interaction is also expressed by vascular cells and seems able to induce pro-inflammatory responses and promote plaque instability. Since no information is yet available on the role of DCs on the activation of vascular smooth muscle cells (VSMCs) the aim of the study was to assess the cellular and molecular mechanisms responsible for the interaction between these cells. DCs were generated from peripheral blood monocytes of healthy donors. Monocytes were sorted by CD14+ magnetic beads selection, cultured for 6 days in medium supplemented with GM-CSF and IL-4 followed by further maturation stimuli (IL-6, IL-1 βα and TNF-α). Monocyte differentiation into DCs was assessed by both microscopic observation and flow cytometry. Cells developed dendritic morphology and expressed high levels of co-stimulatory molecules CD80, CD86, and HLA-DR. Notably about 70% of the cells expressed the DC maturation marker CD83 and CD40. Human VSMCs expressed low levels (1%) of both CD40L and CD40, the latter significantly increased when stimulated with interferon gamma. Moreover, these data were correlated with the adhesion assay which showed a significant adhesion of DCs to human VSMC stimulated with interferon gamma. The preliminary data suggest that the inflammatory environment may stimulate DC and VSMC interaction, leading to their activation.

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